Microsoft Exchange Server

Microsoft Exchange Server is a messaging and collaborative software product developed by Microsoft. It is part of the Microsoft Servers line of server products and is widely used by enterprises using Microsoft infrastructure solutions. Exchange's major features consist of electronic mail, calendaring, contacts and tasks; support for mobile and web-based access to information; and support for data storage.
Planning the migration from Microsoft's internal "legacy XENIX-based messaging system" to Exchange Server environment began in April 1993 , and by January 1995 some 500 users were running on Exchange Server Beta 1. By April 1996 32,000 users were migrated to the environment.

Exchange Server 4.0, released on June 11, 1996, was the original version of Exchange Server sold to the public, positioned as an upgrade to Microsoft Mail 3.5. The original version of Microsoft Mail (written by Microsoft) had been replaced several weeks after Lotus acquired cc:Mail by a package called Network Courier, acquired during the purchase of Consumer Software Inc. in April 1991. Exchange Server was however an entirely new X.400-based client-server mail system with a single database store that also supported X.500 directory services. The directory used by Exchange Server eventually became Microsoft's Active Directory service, an LDAP-compliant directory server. Active Directory was integrated into Windows 2000 as the foundation of Windows Server domains.

On May 23, 1997, Exchange Server 5.0 was released, which introduced the new Exchange Administrator console, as well as opening up "integrated" access to SMTP-based networks for the first time. Unlike Microsoft Mail (which required a standalone SMTP relay), Exchange Server 5.0 could, with the help of an add-in called the Internet Mail Connector, communicate directly with servers using the internet mail standard. Version 5.0 also introduced a new Web-based e-mail interface Exchange Web Access, this was rebranded as Outlook Web Access in a later Service pack. Along with Exchange Server version 5.0, Microsoft released version 8.01 of Microsoft Outlook, version 5.0 of the Microsoft Exchange Client and version 7.5 of Microsoft Schedule+ to support the new features in the new version of Exchange Server.

Exchange Server 5.5, introduced November, 1997, was sold in two editions, Standard and Enterprise. They differ in database store size, mail transport connectors and clustering capabilities. The Standard Edition had the same 16 GB database size limitation as earlier versions of Exchange Server, while the Enterprise Edition had an increased limit of 16 TB (although Microsoft's best practices documentation recommends that the message store not exceed 100 GB). The Standard Edition includes the Site Connector, MS Mail Connector, Internet Mail Service (previously "Internet Mail Connector"), and Internet News Service (previously "Internet News Connector"), as well as software to interoperate with cc:Mail, Lotus Notes and Novell GroupWise. The Enterprise Edition adds an X.400 connector, and interoperability software with SNADS and PROFS. The Enterprise Edition also introduced two node clustering capability. Exchange Server 5.5 introduced a number of other new features including a new version of Outlook Web Access with Calendar support, support for IMAP4 and LDAP v3 clients and the Deleted Item Recovery feature. Exchange Server 5.5 was the last version of Exchange Server to have separate directory, SMTP and NNTP services. There was no new version of Exchange Client and Schedule+ for version 5.5, instead version 8.03 of Microsoft Outlook was released to support the new features of Exchange Server 5.5.

Exchange Server 2000 (v6.0), released on November 29, 2000, overcame many of the limitations of its predecessors. For example, it raised the maximum sizes of databases and increased the number of servers in a cluster from two to four. However, many customers were deterred from upgrading by the requirement for a full Microsoft Active Directory infrastructure to be in place, as unlike Exchange Server 5.5, Exchange Server 2000 had no inbuilt Directory Service, and had a dependency upon Active Directory. The migration process from Exchange Server 5.5 did not have any in-place upgrade path, and necessitated having the two systems online at the same time, with user-to-mailbox mapping and a temporary translation process between the two directories. Exchange Server 2000 also added support for Instant Messaging, but that capability was later spun off to Microsoft Office Live Communications Server. This migration was made significantly easier by Exchange Server 2003 (although still involved the same basic steps); many users of Exchange Server 5.5 waited for the release of Exchange Server 2003 to upgrade. The upgrade process also required upgrading a company's servers to Windows 2000. Some customers opted to stay on a combination of Exchange Server 5.5 and Windows NT 4.0, both of which are no longer supported by Microsoft.

Exchange Server 2007


Exchange Server 2007 was released in late 2006 to business customers as part of Microsoft's roll-out wave of new products. It includes new clustering options, 64-bit support for greater scalability, voice mail integration, better search and support for Web services, better filtering options, and a new Outlook Web Access interface. Exchange 2007 also dropped support for Exchange 5.50 migrations, routing groups, admin groups, Outlook Mobile Access, X.400, and some API interfaces, amongst other features.

Exchange Server 2007 (v8 or with SP1 v8.1) runs on 64-bit x86-64 versions of Windows Server only. This requirement applies to supported production environments only; a 32-bit trial version is available for download and testing. However, companies currently running Exchange Server on 32-bit hardware will be required to replace or migrate hardware if they wish to upgrade to the new version. Companies that are currently running Exchange Server on 64-bit capable hardware are still required to migrate from their existing Exchange 2000/2003 servers to a new 2007 server since in-place upgrades are not supported in 2007.

The first beta of Exchange Server 2007 (then named "Exchange 12" or E12) was released in December 2005 to a very limited number of beta testers. A wider beta was made available via TechNet Plus and MSDN subscriptions in March 2006 according to the Microsoft Exchange team blog.[citation needed] On April 25, 2006, Microsoft announced that the next version of Exchange Server would be called Exchange Server 2007.

Exchange Server 2007 is an integrated part of the Innovative Communications Alliance products.

Key improvements

The principal enhancements, as outlined by Microsoft, are:

* Protection: anti-spam, antivirus, compliance, clustering with data replication, improved security and encryption
* Improved Information Worker Access: improved calendaring, unified messaging, improved mobility, improved web access
* Improved IT Experience: 64-bit performance & scalability, command-line shell & simplified GUI, improved deployment, role separation, simplified routing
* Exchange Management Shell: a new command-line shell and scripting language for system administration (based on Windows PowerShell). Shell users can perform every task that can be performed in the Exchange Server graphical user interface plus additional tasks, and can program often-used or complex tasks into scripts that can be saved, shared, and re-used. The Exchange Management Shell has over 375 unique commands to manage features of Microsoft Exchange Server 2007.
* "Unified Messaging" that lets users receive voice mail, e-mail, and faxes in their mailboxes, and lets them access their mailboxes from cell phones and other wireless devices. Voice commands can be given to control and listen to e-mail over the phone (and also send some basic messages, like "I'll be late")
* Increased the database maximum size limit. Database size is now limited to 16Tb per database.
* Increased the maximum number of storage groups and mail databases per server, to 5 each for Standard Edition (from 1 each in Exchange Server 2003 Standard), and to 50 each for Enterprise Edition (from 4 groups and 20 databases in Exchange Server 2003 Enterprise).

Clustering and high availability

Exchange Server Enterprise Edition supports clustering of up to 4 nodes when using Windows 2000 Server, and up to 8 nodes with Windows Server 2003. Exchange Server 2003 also introduced active-active clustering, but for two-node clusters only. In this setup, both servers in the cluster are allowed to be active simultaneously. This is opposed to Exchange's more common active-passive mode in which the failover servers in any cluster node cannot be used at all while their corresponding home servers are active. They must wait, inactive, for the home servers in the node to fail. Subsequent performance issues with active-active mode have led Microsoft to recommend that it should no longer be used. In fact, support for active-active mode clustering has been discontinued with Exchange Server 2007.

Exchange's clustering (active-active or active-passive mode) has been criticised because of its requirement for servers in the cluster nodes to share the same physical data. The clustering in Exchange Server provides redundancy for Exchange Server as an application, but not for Exchange data. In this scenario, the data can be regarded as a single point of failure, despite Microsoft's description of this set up as a "Shared Nothing" model. This void has however been filled by ISV's and storage manufacturers, through "site resilience" solutions, such as geo-clustering and asynchronous data replication. Exchange Server 2007 introduces new cluster terminology and configurations that address the shortcomings of the previous "shared data model".

Exchange Server 2007 provides built-in support for asynchronous replication modeled on SQL Server's "Log Shipping" in CCR (Cluster Continuous Replication) clusters, which are built on MSCS MNS (Microsoft Cluster Service—Majority Node Set) clusters, which do not require shared storage. This type of cluster can be inexpensive and deployed in one, or "stretched" across two datacenters for protection against site-wide failures such as natural disasters. The limitation of CCR clusters is the ability to have only two nodes and the third node known as "voter node" or file share witness that prevents "split brain" scenarios, generally hosted as a file share on a Hub Transport Server. The second type of cluster is the traditional clustering that was available in previous versions, and is now being referred to as SCC (Single Copy Cluster). In Exchange Server 2007 deployment of both CCR and SCC clusters has been simplified and improved; the entire cluster install process takes place during Exchange Server installation. LCR or Local Continuous Replication has been referred to as the "poor man's cluster". It is designed to allow for data replication to an alternative drive attached to the same system and is intended to provide protection against local storage failures. It does not protect against the case where the server itself fails.

In November 2007, Microsoft released SP1 for Exchange Server 2007. This service pack includes an additional high-availability feature called SCR (Standby Continuous Replication). Unlike CCR which requires that both servers belong to a Windows cluster, typically residing in the same datacenter, SCR can replicate data to a non-clustered server, located in a separate datacenter.

Licensing

Like Windows Server products, Exchange Server requires Client Access Licenses, which are different from Windows CALs. Corporate license agreements, such as the Enterprise Agreement, or EA, include Exchange Server CALs. It also comes as part of the Core CAL. Just like Windows Server and other server products from Microsoft, you can choose to use User or Device CALs. Device CALs are assigned to a device (workstation, laptop or PDA). User CALs, are assigned to a user or employee (not a mailbox). User CALs allow a user to access Exchange e-mail from any device. User and Device CALs are the same price, however cannot be used interchangeably. For Service Providers looking to host Microsoft Exchange, there is an SPLA (Service Provider License Agreement) available whereby Microsoft receives a monthly service fee in the place of the traditional Client Access Licenses. Two types of Exchange CAL are available: Exchange CAL Standard and Exchange CAL Enterprise. The Enterprise CAL is an add-on licence to the Standard CAL.